Thermal relay



Aug.l14, 192s.

A. J.l MOTTLAU THERMAL RELAY' Filed sept. '28,. 1926.

2 sheets-sheet. 2

WITN ESS ES AT'TORNEY Patented `1.4, 1928.

UNITED] STATES AUGUST J. 'MOTTLAU, OF PITTSBURGH, PENNSYLVANIA AsSIGNORv To WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION or PENNSYL- VANIA Y THERMAL RELAY. i

Application filed September 28, 1928. -Serial Nq. 138,189.

My invention relates to circuit-protective devices and particularly to thermal relays.

An object ofjmy invention 1s to provide a thermal relay that shall not be operatively affected by ambient temperature.`

Another object of my invention 1s toprovide a thermal relay thatlshall permit of such adjustment as to -be operable over a relatively wide range of thermal conditions.

Another object of my Sinvention 1s to provide a thermal relay'that shall actuate the contact members associated therewith into and out of engagement with a snap motion. In practicing my invention,` I provide a pair of bimetallic members that are opera.

tively secured together at corresponding Y ends thereof and a bridging member of substantially sinuous shape disposed between the other ends thereof and operatively secured thereto. A stationary contact member is mounted on one of the bimetallic members, and a movablecontact memberis mounted on the bridging member. The bimetallic members are so disposed that they are deflected in the same direction vwhen subjectedv to the same temperature. Means are provided also for adjustably moving the ends,

vto vwhich -the operating member is secured,

away from or towards each other in accordance with predetermined thermal condltions at which the bimetallic members shall be operable to actuate the bridging member laterally between the ends thereof. A heating coil is thermally associated with one of the "bimetallic members for heating it in aocordance with conditions in an electric translating deviceto be protected. The heating coil may beiincluded in the circuit of the translating device.

V In the drawings: i f

Fig. 1 -is a front view of a device embodying my invention;

Fig. 2 is a top plan view thereof;

Fig. 3 is a view, in section, of the device illustrated in Fig. 1, taken on the lines IIL-III thereof; Fig. 4 is a view of the device illustrated -in Fig.- 1 actuated to a 'position corresponding to a certain ambient temperature condition; and

Fig. 5 is a view ofV thedevice illustrated shOWn) in the portions 21 of prises a.v base member 12, a pair of bimetallic members 13 and 14 mounted thereon, and a bridging member 15, of sinuousshape, secured between the ends 16 and 17 .of the bimetallic members by suitable means, such as rivets 18. l

The bime/tallic members 13 and 14 are of substantially L-shape having longer portions- 19, and portions 20 of less length extending substantially at right angles to the portions 19, and upturned portions 21 which are secured together by a spacin member 22 and a pin member 23 the en s of which are hammered over the portions 21. The bimetallic member 14 is directly secured to 22 and -23. f

A stationary contact mechanism 24 is secured to the elongated portion 19 of the bimetallic member 17 by a suitablescrew member 25 that serves to clamp the bimetallic member securely against an apertured portion 26 of the mechanism 24. The member 24 is provided with an extended portion 27 at the end of which a pair of contact members 28 and 29 are'insulatedly secured. The contact members 28 and 29 extend through the end of the portion 27 and are insulated therefrom by insulating washers 31 and secured thereto by nut members 32 that register with the screw threaded portions 33 and 34 of the terminal members 28 and 29. Conductors 35 may be connected to the terminal members 28 and 29 and to av control device for controlling an electric-energy translating device.

The bridging member 15 is provided with a contact member 36 which, in its operative position, as illustrated in Fig. 1, so .bridges the contact members 28 and 29 that they are connected in series.

If it is desirable to increase or to decreas the longitudinal pressure on member 15, the ends 16 and 17 may be moved towards or away from eachotherby turning a screwthreaded adjusting member 37 in the proper direction. The screw-threadedy adjusting means 37 registers with, `and' extends through, screw-threaded apertures (not the bimetallic members l13 and 14.v

illustrated in the drawings, is so arranged yIl of the drawings.

that the sides 38 and39 of the bimetallic members 13 and 14 are the high-expansion 4bient*'temperature of a suiiiciently high value, they will be deflected to a. general position substantially as illustrated in Fig. If one 'of the members, for instance, the member 13, is thermally energized to a higher temperatureby asuitable heating coil 43. that is in circuit with a `translating device not shown, the member' 13 will be deected to such position that the member 15 will be caused to assume a position illustrated in Fig. 5 of the drawings when a predetermined current condition obtains in the .translating device. When 1n this position, the vcontact member 36 is out of engagement with the contact members 28 -and 29. Since the contact members 28 and 29 are in circuit with the control device, when in the position illustrated in Figs. 1, 3 and 4 of the'drawings, it is evident that the control device will become deenergized when the contact member 36 is in the posi-- tion illustrated in Fig. 5.

If it is desirable that the thermal relay 11 I shall be operable when a relatively small .thereby produce an initial longitudinal compression in the member 1'5. Itis, therefore, evidentthat a relatively small expansion of the bimetallic member 13 is required to disengage the contact member 36 from the contact members 28 and 29.

If it is desirable that a large current shall traverse the coil 43 to actuate the thermal relay to the position illustrated in Fig. 5 of the drawings, it is only necessary to turn the adjusting means 37 in such direction that the ends'16 and 17 shall be moved away from each other. Therefore, a correspondingly vlarge deflection of the member 13 will be necessary before the bridging member 16 is sufliciently compressed to actuate it to the position illustrated in Fig. 5 of the drawings.

My invent-ion provides a relatively simple thermal relay'that consists of a small number of parts and is easily manufactured. The

-device may be so adjusted as to be operable over a relatively wide range of conditions to be controlled and is so constructed that ambient temperature vhas substantially no effect upon its operation.

The invention comprises, in general, a pair of spaced-apart bimetallic members that are adapted to actuate a. resilient bridging member into and out of engagement with a pair of relatively stationary contact members.

One of the bimetallic members is provided I with a heating coil which is thermally ener gized in accordance with the current flowing in a circuit to be protected. Since one of the members is energized more than the other, the member receiving thel greater amount of thermal energy will be deflected to thereby actuate the' Contact members on bridging member out of. engagement with the stationar Contact members.

arious .modifications may be made in the device embodying my invention without vdeparting: from the spirit andthe scope thereof. ldesire, therefore, that only such limitations shall be placed thereon as are im-- posed bythe prior art and the lappended claims.

I claim as my invention: 1. The combinationwith a resilient bridging member of'substantially sinuous shape, a contact member mounted thereon, apair of bimetallic'members for supportingsaid re-v other as todeiiect in substantially the saine direction when subjected to the same ambient temperature variations, and a stationary contact member supported byV one of said bi- -metallic .members in operative relation to the other Contact member, of means for thermally energizing one of the bimetallic inembers tocause it to actuate the bridging member to control the engaged and disengaged position of said contact members.

-2. The combination with apair o f bimetallic supports disposed to maintain the distance therebetween substantially constant for all values of ambient temperatures, a resilient bridging memberA of substantially sinuous shape disposed between the supports in operative engagement therewith, and

means for varying the initial distance between'said supports, of means for thermally energizing one of said bimetallic supports more than the other to cause the -bridging member to be deflected laterally between the supports.

3. The combination with a pair of bimetallic members- .of substantially L-shape, means for holding the shortlegs of said members relatively fixed, 'a resilient member of substantially sinuous shape disposed between the`long legs thereof, and a contact member mounted in operative relation to the members disposed to be deflected in the same directionfin response to ambient temperatures, means for adgustably securing corresponding ends of said members in operative cause `said bridging member to be ldeiected relation to each other, and a. resilient bridgwith a snap motion.

ing member having recurring substantially In testimony whereof, I have hereunto sub- 10 similar curvedportions for operatively assoscribed my name this 13th -day of Septemciating with a stationary contact member, of ber, 1926.

thermal means for energizing one of said biv metallic members more' than the other to AUGUST J. MOTTLAU. 

